David scbymgeoue



(No Model) L 1). SORYMGEOUR. FRAME FOR SCHOOL SLATES.

N0. 376,786. Patenjed 8811.24, 1888.

\M'kHEEEEE U ITED STATES PA E T OFFICE."

DAVID SORYMGEOUR, or Morison, MAINE, Assicnoa TO THE PARAGON NOISELESSsoHooL SLATE COMPANY, or SAME PLACE.

FRAMEFORSCHOOL-SLATES.

SPECIFICATION forming part of Lettes Patent No. 376,786, dated January24, 1888.

7 Application filed Jnre 4. 1887. Serial No. 240,252, (X model.) i

To all whom it may concern:

Be 1t known that 1, DAVID SORYMGEOUR, of M onson, 1n the county ofPiscataquis and State of Maine, have invented certain new and use-- fulImprovements'in Frames forSchool-Slates; and I do hereby declare thatthe'following is a full, clear, and exact description of the same,referencebeing had to the ac'companyingdrawngs, forming a part of thisspecification, and

IC 1n which- 7 Figure 1 represents an isometric view of aschool-slateembodyingmyimprovements. Fig. 2 1s a cross or transversesection thereof, upon an enlarged scale, taken on line a a, Fig. 1, r 5wlth the central porti'onofthe slate and frame broken away. Fig. 3represents part of a thin, fiat, metallic strip, such as is used in theconstruction of my improvedslate-frame. Fig. 4 representssaid stripafter having been cut into thedesired shape to form one of the cornersof the frame, hereinafter more fullydescribed; and Figs. 5 and 6represent a side and edge v ew, respectively, of one of the cornersofthe frame made from a cut strip, such as'shown in Fig. 4, after havingbeen bent into the proper form and prior to being covered with rubber,as will also be hereinafter explained.

The object of my invention is to produce a school-slate frame, whichshall be noiseless as well as elastic, so that it may not be easily vbroken when dropped upon any hard substance, and that will not readilyslide upon or scratch any smooth surface upon which it may be placedwhen in use.

Said invention relates more especially to improvements upon theslate-frame for which Letters Patent of the United Stateslwere grantedme May 8, 1883, and numbered 277,16l.

My 1nvention consists in combining'with the 4o edges of an ordinaryslate a hollow frame I madepreferably of thin sheet metal, cut and bentin a peculiar manner to produce circular outer and square inner cornershaving smooth unwrinkled surfaces, and covered with'rubber vulcanizedand molded into the desired shape, as hereinafter more fully set forth.

To enable others skilled in the art to which my invention. appertains tobetter understand the nature and purpose thereof, I, will now proceed todescribe it more in'detail.

' Referring to the drawings, the part marked 7 1) represents an ordinaryschool-slate,andc

my improved frame, which is constructed and applied to the edges of saidslate in the follow Theframe 0 comprises an inner 55,

ing manner. supportingandstiffeninghollowcasing,d,made preferably ofthinsheet metal,'and coated upon the exterior with vulcanized rubber e, asbefore stated. i

In making the casings d, the sheet metal is 63 first cut into stripssimilar to the piece'f, shown in Fig. 3, and of the proper widths andlengths to form the desired sizes and widths of frames. Said strips arethen cut, by means of suitables dies, into substantially the shape 65shown in Fig. 4, and atthe proper places to produce the corners, eachcorner, it will'be understood, being cut as shown in said Fig. 4. J Thestrips having been thus cut-,are now bent in any suitable manner intothe shapes shown in" Figs. 2, 5, and 6, ready to be applied to the edgesof the slates. r Bycuttingand bending the strips inthe manner shown itwill be'observed that the straight edges 9 form the miter-joints g. Thev curved edges h, the rounded corners h ,.and

the central narrow connecting-strips, i, which extend around the cornersaforesaid, serve to hold the parts j of the metallic casing together andto protect the corners of the slate when 86 ing of rubber, which isapplied in the follow- 90 I ing manner, and substantially asdescribed-in my formerpatent previously cited. The rnbher in anunvulcanized state is first fitted over' the casing, the same beingextended nnder'the inner edges, k k, thereof, next to the slate, as 5shown inFig. 2. Itis then subjected topressinc and heat .whilein contactwith sulphur by I I means of a pair of molds, one upon each side of theframe, whose outer contour corresponds to the shape desired to beimparted to said ICO' frame. V This process causes therubber to bevulcanized or hardened, so that itwill retain permanently the shapeimparted to it, and also to adhere with great tenacity to the surface ofthe metal casing, as well as to the edges of the slate, therebyeffectually preventing dirt and other foul and filthy matter fromentering under the edges of the frame when in use, which obviates aserious objection in many of the old slates, and notably those havingwooden frames. Being thus constructed,it may therefore be easily keptclean and free fromallimpurities, and the frame being both strong andelastic greatly reduces the liability to breakage of the slate, as wellas rendering it as nearly noiseless as is possible.

Another advantage which the frame possesses over the usual wooden framesis that it retains its position wherever placed without slipping,consequently not requiring to be held while in use. By thus adhering tothe surface upon which it is placed the slate is not liable to be pushedoff upon the floor and broken.

The casing d, although made of light stock, is strong and not easilybent, owing to the ribs d d, formed longitudinally thereon, as shown inFig. 2; and, if desired, additional strength may be imparted thereto bymaking the same with two or more ribs or corrugations, instead of asshown. Said ribs constitute one of the important features of myinvention, as I am enabled to obtain the requisite strength with lighterstock, and thereby reduce the cost of the frames. I do not, however,limit myself to said construction, as it does not constitute anessential feature of said invention; but I do limit myself to the mannerof forming the corners of the frame, substantially as shown anddescribed, and to the method of applying the outer rubber coating 7 tosaid frame, as previously specified, and

pointed out in the claims.

I thus limit my invention in view of the United States Patent No.360,327, granted to Peter G. Ritchie, for improvements in school- By theemployment of a sheet-metal casing,

as described and shown in my present application, instead of a wire,asin my former patent, I am enabled to obtain the desired shape of framewith a largesaving in rubber, while at the same time producing a muchstronger frame.

What I claim is 1. A frame for school-slates, consisting of an innersupporting-case made from a strip of sheet metal or equivalent materialof proper width and length, out to form the corners,w1th mitered sides,rounded edges, and the narrow connecting-strip over each corner, thenbent and fastened over the edges of the slate, and an outer coating ofrubber or similar elastic material enveloping said case and extendingunder the edges thereof,substantiall y as shown and specified. v 2. Aschool -slate, in combination with a frame comprising an innersupporting-case made from astrip of sheet metal or equivalent materialof proper width and length, cut to form the corners,with' mitered sides,rounded edges, and the narrow connecting-strip over each corner, thenbent and fastened over the edges of said slate, and an outer coating ofrubber or similar elastic material enveloping said case and extendingunder the edges thereof, substantially as shown and specified. 3. Themethod of making and attaching a frame to a school-slate, consisting incutting and bending a strip of sheet metal or equivalent material ofproper width and length into the proper form to produce an innersupporting-case having rounded corners, mitered at the sides, and anarrow connecting-strip over each corner, then fitting said case overthe edges of the slate with the ends thereof brazed or solderedtogether, then enveloping its outer surface with unvulcanized rubber,extending the same under the edges thereof, and finally subjecting saidcoated case or frame to pressure and heat between suitable molds and incontact with sulphur, thereby causing the rubber to be molded,vulcanized, and to adhere tightly to the metal casing, as well as to theedges of the slate, substantially as and for the purposes set forth.

DAVID SORYMGEOUR.

'Witnesscs:

R. C. PENNEY, W. E. J ONES.

